Serum Alkaline Phosphatase in Cystic Fibrosis; Interpretation of Elevated Values Based on Electrophoretic Isoenzyme Analyses

Abstract

Sera from 31 of 146 patients with cystic fibrosis (CF) contained levels of serum alkaline phosphatase (AP) which were elevated by age-related criteria. Prominent liver isoenzyme bands were present after polyacrylamide gel electrophoresis of all 31 abnormal sera. Larger than normal amounts of bone and intestinal AP were not present in these sera. These findings indicate that liver abnormalities consistently are responsible for elevations of total AP in sera of patients with CF. Several causes of high liver AP levels in CF patients were identified: chronic hepatic congestion, drug hepatotoxicity, overt biliary cirrhosis, and most commonly subclinical focal biliary cirrhosis.